Mitt Romney homed in on Barack Obama's most vulnerable political spot – the continued struggle for economic revival – in accusing him of creating "shameful" divisions and overseeing three years of decline in a prebuttal of the president's state of the union address on Tuesday night.

Obama is expected to focus on his call for a new economic stimulus package aimed at creating millions of new jobs. But speaking in cavernous Tampa warehouse belonging to a company that was closed by the recession in 2008, Romney said that will only make things worse.

"Three years ago, we measured candidate Obama by his hopeful promises and his slogans. Today, President Obama has amassed an actual record of debt, decline and disappointment," he said. "This president's agenda made these troubled times last longer. Instead of solving the housing crisis and getting Americans back to work, President Obama has been building a European-style welfare state."

Standing under an 'Obama Isn't Working' banner - adapted from Margaret Thatcher's successful 1979 election campaign in the UK – Romney went on to accuse Obama of class warfare.

"Tonight we're going to be treated to more divisive rhetoric from a desperate campaigner-in-chief. It's shameful for a president to use the state of the union to divide our nation," he said.

But the Republican contender made no mention of his divisive position as one of the richest men in the country paying tax at a rate far below that of most Americans after the release of his tax returns showed he paid just 15% tax on $45m of income over the past two years, mostly from investments.

Romney said Obama is overseeing continued mass unemployment in order to save one job – his own.

"The unemployed won't get tickets to to sit next to the first lady. Instead tonight the president will do what he does best. He'll give a nice speech full of memorable phrases. But he won't give you the hard numbers like 9.9% unemployment in Florida. Or 25%. That's the number of foreclosed homes in America that are here in Florida," he said.

Romney said that he expects Obama to blame a "do-nothing Congress", with the House of Representatives under Republican control, for the his administration's failure to revive the economy. But, Romney said, for two years Obama's own party controlled both houses of Congress and he did little.

"Did he fix the economy? No. Did he tackle the housing crisis? No," he said.

"He believes the party of big government … He's wrong, we're right."

Romney said that instead Obama spent trillions of dollars on economic stimulus, passed expensive health care reforms and took over car manufacturers.

"He spearheaded one of the largest expansions of government in American history. And he's paying for all that with money he's borrowed from China," he said.

Romney did not offer anything new in his own proposals, saying that as president he will impose smaller, more efficient government by cutting spending and repealing regulations.

"As president I will cut spending, I will cap spending and I will finally balance the budget," he said.

Barack Obama has drawn a line between himself and the Republicans before the US elections, promising to build a fairer America and to ensure the rich pay no less in tax than ordinary working people do. He emphasised foreign policy successes including pulling out of Iraq and the killing of Osama bin Laden. In an emotional moment, the US president hugged Gabrielle Giffords, the congresswoman who is recovering from being shot in the head last year